1. Field of the Application
The present invention relates to superhard materials, and more particularly to a superhard composite material.
The invention is readily adaptable for application in machine-tool industry and other industries where it is necessary to perform cutting of high-duty cast irons, hardened steels and difficult-to-work alloys.
2. Description of the Prior Art
For example, there is known a composite material which comprises cubic boron nitride and alkali-earth metal boride. This material is homogeneous in structure and is fairly resistant to wear. However, the material mentioned above has low heat conductivity, the feature adversely effecting the performance characteristics of the cutting tools manufactured from this material as the cutting surfaces are overheated in the process of machining.
In addition, the material referred to above is electrically nonconductive, which necessitates the provision of a carbon-graphite heater in a high-pressure chamber the working volume of which is thereby substantially reduced and a uniform temperature field is not ensured in the sample being produced.
There is also known a composite material which comprises boron nitride and a binder consisting of carbides and borides of a metal selected from the group IV-VIII of the periodic system. The above-mentioned material shows fairly high brittleness when employed, for example, in the manufacture of cutting tools used for intermittent machining of steels and cast iron. In addition, the compounds and mixtures thereof used as a binder, require high sintering which, in turn, necessitates high pressure to be applied in the process of production of the above-mentioned composite material. The disadvantage inherent in this material makes it difficult to produce large-size samples and renders the sample manufacturing process less efficient.